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Global and local condensate and superfluid fractions of a few hard core bosons in a combined harmonic optical cubic lattice in continuous space

  • Asaad R. SakhelEmail author
Regular Article

Abstract

We explore the global and local condensate and superfluid (SF) fractions in a system of a few hard core (HC) bosons (N = 8 and N = 40) trapped inside a combined harmonic optical cubic lattice (CHOCL) in continuous space at T = 0 K. The local condensate fraction (CF) is computed for individual lattice wells by separating the one-body density matrix (OBDM) of the whole system into components at the various lattice sites. Then each “lattice-site” component is diagonalized to find its eigenvalues. The eigenvalues are obtained by a method presented earlier [J.L. DuBois, H.R. Glyde, Phys. Rev. A 63, 023602 (2001)]. The effects of overlap between the condensates in the lattice wells on the CF in one well is also investigated. The SF fraction (SFF) is calculated for N = 40 only by using the diffusion formula of Pollock and Ceperley [Phys. Rev. B 36, 8343 (1987)]. Our chief result is an opposing behavior of the global and local CF and SFF with increasing lattice wave vector k. In addition, the CF in a lattice well is enhanced by the overlap with its neighbor wells beyond the result when the overlap is neglected. The global SF is depleted with a rise of the repulsion between the bosons, yet at very strong interaction superfluidity is still present. The global CF remains almost constant with increasing HC repulsion.

Keywords

Cold Matter and Quantum Gas 

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Copyright information

© EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  1. 1.Faculty of Engineering Technology, Applied Sciences DepartmentAl-Balqa Applied UniversityAmmanJordan

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